AR10... 6.5 or .308?

[Boman21]

I really really appreciate all the info, experiences, and advice! I definitely got more than I was expecting. From all the info, I'm definitely leaning the .308 direction. I'll give an update when I make a decision and start putting it together. If I can find parts

 

[Randy1950]

I've got an upper and a lower for an AR 10 build. Trying to make a decision on which direction to go, 6.5 Creedmor or .308. Looking for some help from someone that has experience with AR10s that could nudge me one way or the other with their experiences. I want to use it for long range applications. This will be my first build so any advice would be much appreciated!

 

[Randy1950]

I give the edge to the 6.5 CM. I think it has the ballistic edge over .30 cal. That's my story and I am sticking to it.

 

[ntsqd]

On the Adjustable gas block front, I went with a Superlative Arms block and I couldn't be happier with it. I started out with it closed down and slowly opened it up until the rifle cycled smoothly. Since then I've only shot similar factory loads and the rifle has cycled as it should. Given how easy it was to tune it to this range of loads it wouldn't be a big deal to tune it to others.

 

[Pro2A]

I've got an upper and a lower for an AR 10 build. Trying to make a decision on which direction to go, 6.5 Creedmor or .308. Looking for some help from someone that has experience with AR10s that could nudge me one way or the other with their experiences. I want to use it for long range applications. This will be my first build so any advice would be much appreciated!

Assuming you won't be needing the "firepower" of the semi-auto for clearing rooms or stopping spooks in the wire, why not make a straight pull bolt only or bolt/semi set up? Run an adjustable gas block ON-OFF for semi/bolt. Run a side charging bolt/upper for straight pull. For bolt only, eliminate the gas block, gas tube, gas key on bolt; use special ordered barrel without gas port machined. These deletes yield a truly free float barrel for best accuracy.......those deletes touching the barrel on ARs is a significant source of AR typically lower accuracy. Bolt only in AR15 platform is very accurate in 224 Valkyrie and 6MM ARC. Similar results available in the AR10 platform with attending longer COAL. Bolt only also eliminates operational issues and tuning.

 

[diamonddave2]

The Unitah Precision uppers would work that way too https://uintahprecision.com/product/upr10/
I prefer the lower recoil of the auto loader. I recently put a Kalikey on my 300 BLK Pistol and it is very accurate. It just isn't as soft shooting as before, even subsonic. If I could run a moderator here in Commifornia it would make it really quiet.

 

[norinco982lover]

I'd just pick one and build it. You can change barrels extremely easily later.

that having been said, I'd love to do a 6.5 all of the AR10's I've owned were .308

 

[Fl cracker]

308 all day and on sunday. More ammo choices, Bigger bullet, more knock down power, not knocking the 6.5 but out to 500 600 yards the 308 out performs 6.5 across the board. If doing 6.5 get a bolt gun. my 308 ar10 psa is 1 to 1.5 in moa with factory 150 grain win. Power points box ammo. You cant beat a 30 caliber bullet

 

[Bullitthead]

I went with the 6.5 Creedmoor. It tends to shoot around 1 MOA sometimes more sometimes less. I can ring an eight inch steel plate at 500 yards with good consistency. That is when the wind cooperates. Here in the panhandle we only get a calm day once in a proverbial blue moon so the 6.5 was a no brainer for me. Nothing like shooting in a 10 mph crosswind with intermittent 25 mph gusts to make you feel like you can't hit the broad side of a barn. If you do go with Creedmoor look into the high pressure bolt with smaller firing pin mine kept stamping holes in the primers even at moderate pressure's. Whatever you chose you might be surprised how accurate a gas gun can shoot with quality components.

 

[arch408]

My vote is the 6.5 CM. But if you want you could build both and swap them out on a lower, Shilen will build a match quality barrel mated to a bolt that will insure perfect headspace which should guarantee the best accuracy. Also, they can match that same bolt to different barrels. So, you can have several match quality uppers that use the same bolt. Just swap out the Blot Carrier Group when you change out the uppers.

 

[diamonddave2]

Interesting, the place where I got my .308 out to 300 yds is ~19 miles south of you off Mines Road. The land owners there have had ferral pig problems, but they're getting it under control.

I'd love a chance at shooting some of those pigs if you ever need another partner. You're right, Im in Livermore. I just drove up Mines road last Thursday.

 

[DWier]

I shoot at a good friend's home range. Reaches out to 800m. He's a retired SEAL team sniper. He shoots 556 and 308. I showed up at his place with a 6.5cm tactical rig. He said 'cool, what caliber, I said 6.5 creed. His response was classic. "Thats cheating".

 

[bamban]

You guys are missing a good fun. Take a 223 at 1000 yards paper punching, shoot 80s or 85.5s with your 7T barrels.

 

[FreeNHim]

I had a Daniel Defense DD5V1 with BOTH v1308 and v4 6.5 CM uppers. They were both awesome.